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Message-ID: <20250410001747.1844-1-yohan.joung@sk.com>
Date: Thu, 10 Apr 2025 09:17:15 +0900
From: "yohan.joung" <yohan.joung@...com>
To: "yohan.joung" <yohan.joung@...com>
Cc: pilhyun.kim@...com,
	linux-kernel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net,
	jaegeuk@...nel.org,
	chao@...nel.org,
	daeho43@...il.com
Subject: Re: [f2fs-dev] [PATCH v1] f2fs: Improve large section GC by locating valid block segments

hi jeageuk, chao 
How about changing the large section gc in this direction?
Thanks

> Change the large section GC to locate valid block segments instead of
> performing a sequential search. This modification enhances performance
> by reducing unnecessary block scanning in large storage sections.
> 
> example :
> [invalid seg 0] [invalid seg 1] [invalid seg 2]
> [  valid seg 3] [  valid seg 4] [  valid seg 5]
> 
> Current: In the first GC, nothing is moved,
> but in the second GC, segments 3, 4, and 5 are moved.
> Change: In the first GC, segments 3, 4, and 5 are moved.
> 
> Signed-off-by: yohan.joung <yohan.joung@...com>
> ---
>  fs/f2fs/f2fs.h  |  2 ++
>  fs/f2fs/gc.c    | 92 +++++++++++++++++++++++++++++++++++--------------
>  fs/f2fs/gc.h    |  6 ++++
>  fs/f2fs/super.c |  8 ++++-
>  4 files changed, 82 insertions(+), 26 deletions(-)
> 
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index f1576dc6ec67..348417edac25 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -4008,6 +4008,8 @@ int f2fs_gc_range(struct f2fs_sb_info *sbi,
>  int f2fs_resize_fs(struct file *filp, __u64 block_count);
>  int __init f2fs_create_garbage_collection_cache(void);
>  void f2fs_destroy_garbage_collection_cache(void);
> +int __init f2fs_init_garbage_collection_summary_cache(void);
> +void f2fs_destroy_garbage_collection_summary_cache(void);
>  /* victim selection function for cleaning and SSR */
>  int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
>  			int gc_type, int type, char alloc_mode,
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 2b8f9239bede..3b63e85fa038 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -24,6 +24,7 @@
>  #include <trace/events/f2fs.h>
>  
>  static struct kmem_cache *victim_entry_slab;
> +static struct kmem_cache *gc_page_entry_slab;
>  
>  static unsigned int count_bits(const unsigned long *addr,
>  				unsigned int offset, unsigned int len);
> @@ -711,6 +712,30 @@ static void release_victim_entry(struct f2fs_sb_info *sbi)
>  	f2fs_bug_on(sbi, !list_empty(&am->victim_list));
>  }
>  
> +static struct gc_page_entry *add_gc_page_entry(struct list_head *gc_page_list,
> +					struct page *sum_page, unsigned int segno)
> +{
> +	struct gc_page_entry *gpe;
> +
> +	gpe = f2fs_kmem_cache_alloc(gc_page_entry_slab, GFP_NOFS, true, NULL);
> +	gpe->segno = segno;
> +	gpe->sum_page = sum_page;
> +	list_add_tail(&gpe->list, gc_page_list);
> +	return gpe;
> +}
> +
> +static void release_gc_page_entry(struct list_head *gc_page_list, bool putpage)
> +{
> +	struct gc_page_entry *gpe, *tmp;
> +
> +	list_for_each_entry_safe(gpe, tmp, gc_page_list, list) {
> +		if (putpage)
> +			f2fs_put_page(gpe->sum_page, 0);
> +		list_del(&gpe->list);
> +		kmem_cache_free(gc_page_entry_slab, gpe);
> +	}
> +}
> +
>  static bool f2fs_pin_section(struct f2fs_sb_info *sbi, unsigned int segno)
>  {
>  	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
> @@ -1721,14 +1746,18 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>  	struct page *sum_page;
>  	struct f2fs_summary_block *sum;
>  	struct blk_plug plug;
> +	struct gc_page_entry *gpe;
>  	unsigned int segno = start_segno;
>  	unsigned int end_segno = start_segno + SEGS_PER_SEC(sbi);
>  	unsigned int sec_end_segno;
> +	unsigned int window_granularity = 1;
>  	int seg_freed = 0, migrated = 0;
>  	unsigned char type = IS_DATASEG(get_seg_entry(sbi, segno)->type) ?
>  						SUM_TYPE_DATA : SUM_TYPE_NODE;
>  	unsigned char data_type = (type == SUM_TYPE_DATA) ? DATA : NODE;
>  	int submitted = 0;
> +	int gc_list_count = 0;
> +	LIST_HEAD(gc_page_list);
>  
>  	if (__is_large_section(sbi)) {
>  		sec_end_segno = rounddown(end_segno, SEGS_PER_SEC(sbi));
> @@ -1744,7 +1773,7 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>  					f2fs_usable_segs_in_sec(sbi);
>  
>  		if (gc_type == BG_GC || one_time) {
> -			unsigned int window_granularity =
> +			window_granularity =
>  				sbi->migration_window_granularity;
>  
>  			if (f2fs_sb_has_blkzoned(sbi) &&
> @@ -1752,8 +1781,6 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>  					sbi->gc_thread->boost_zoned_gc_percent))
>  				window_granularity *=
>  					BOOST_GC_MULTIPLE;
> -
> -			end_segno = start_segno + window_granularity;
>  		}
>  
>  		if (end_segno > sec_end_segno)
> @@ -1762,37 +1789,38 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>  
>  	sanity_check_seg_type(sbi, get_seg_entry(sbi, segno)->type);
>  
> -	/* readahead multi ssa blocks those have contiguous address */
> -	if (__is_large_section(sbi))
> +	for (segno = start_segno; segno < end_segno; segno++) {
> +		if (!get_valid_blocks(sbi, segno, false))
> +			continue;
> +
> +		/* readahead multi ssa blocks those have contiguous address */
>  		f2fs_ra_meta_pages(sbi, GET_SUM_BLOCK(sbi, segno),
> -					end_segno - segno, META_SSA, true);
> +				window_granularity, META_SSA, true);
>  
> -	/* reference all summary page */
> -	while (segno < end_segno) {
> -		sum_page = f2fs_get_sum_page(sbi, segno++);
> +		/* reference all summary page */
> +		sum_page = f2fs_get_sum_page(sbi, segno);
>  		if (IS_ERR(sum_page)) {
>  			int err = PTR_ERR(sum_page);
> -
> -			end_segno = segno - 1;
> -			for (segno = start_segno; segno < end_segno; segno++) {
> -				sum_page = find_get_page(META_MAPPING(sbi),
> -						GET_SUM_BLOCK(sbi, segno));
> -				f2fs_put_page(sum_page, 0);
> -				f2fs_put_page(sum_page, 0);
> -			}
> +			release_gc_page_entry(&gc_page_list, true);
>  			return err;
>  		}
> +		add_gc_page_entry(&gc_page_list, sum_page, segno);
>  		unlock_page(sum_page);
> +		if (++gc_list_count >= window_granularity)
> +			break;
>  	}
>  
>  	blk_start_plug(&plug);
>  
> -	for (segno = start_segno; segno < end_segno; segno++) {
> +	list_for_each_entry(gpe, &gc_page_list, list) {
>  
>  		/* find segment summary of victim */
> -		sum_page = find_get_page(META_MAPPING(sbi),
> -					GET_SUM_BLOCK(sbi, segno));
> -		f2fs_put_page(sum_page, 0);
> +		sum_page = gpe->sum_page;
> +		segno = gpe->segno;
> +		if (!sum_page) {
> +			f2fs_err(sbi, "Failed to get summary page for segment %u", segno);
> +			goto skip;
> +		}
>  
>  		if (get_valid_blocks(sbi, segno, false) == 0)
>  			goto freed;
> @@ -1835,18 +1863,20 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
>  				get_valid_blocks(sbi, segno, false) == 0)
>  			seg_freed++;
>  
> -		if (__is_large_section(sbi))
> -			sbi->next_victim_seg[gc_type] =
> -				(segno + 1 < sec_end_segno) ?
> -					segno + 1 : NULL_SEGNO;
>  skip:
>  		f2fs_put_page(sum_page, 0);
>  	}
>  
> +	if (__is_large_section(sbi) && !list_empty(&gc_page_list))
> +		sbi->next_victim_seg[gc_type] =
> +			(segno + 1 < sec_end_segno) ?
> +				segno + 1 : NULL_SEGNO;
> +
>  	if (submitted)
>  		f2fs_submit_merged_write(sbi, data_type);
>  
>  	blk_finish_plug(&plug);
> +	release_gc_page_entry(&gc_page_list, false);
>  
>  	if (migrated)
>  		stat_inc_gc_sec_count(sbi, data_type, gc_type);
> @@ -2008,6 +2038,18 @@ int f2fs_gc(struct f2fs_sb_info *sbi, struct f2fs_gc_control *gc_control)
>  	return ret;
>  }
>  
> +int __init f2fs_init_garbage_collection_summary_cache(void)
> +{
> +	gc_page_entry_slab = f2fs_kmem_cache_create("f2fs_gc_page_entry",
> +					sizeof(struct gc_page_entry));
> +	return gc_page_entry_slab ? 0 : -ENOMEM;
> +}
> +
> +void f2fs_destroy_garbage_collection_summary_cache(void)
> +{
> +	kmem_cache_destroy(gc_page_entry_slab);
> +}
> +
>  int __init f2fs_create_garbage_collection_cache(void)
>  {
>  	victim_entry_slab = f2fs_kmem_cache_create("f2fs_victim_entry",
> diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
> index 5c1eaf55e127..9c8695efe394 100644
> --- a/fs/f2fs/gc.h
> +++ b/fs/f2fs/gc.h
> @@ -82,6 +82,12 @@ struct victim_entry {
>  	struct list_head list;
>  };
>  
> +struct gc_page_entry {
> +	unsigned int segno;
> +	struct page *sum_page;
> +	struct list_head list;
> +};
> +
>  /*
>   * inline functions
>   */
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index f087b2b71c89..a3241730fe4f 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -5090,9 +5090,12 @@ static int __init init_f2fs_fs(void)
>  	err = f2fs_create_garbage_collection_cache();
>  	if (err)
>  		goto free_extent_cache;
> -	err = f2fs_init_sysfs();
> +	err = f2fs_init_garbage_collection_summary_cache();
>  	if (err)
>  		goto free_garbage_collection_cache;
> +	err = f2fs_init_sysfs();
> +	if (err)
> +		goto free_garbage_collection_summary_cache;
>  	err = f2fs_init_shrinker();
>  	if (err)
>  		goto free_sysfs;
> @@ -5141,6 +5144,8 @@ static int __init init_f2fs_fs(void)
>  	f2fs_exit_shrinker();
>  free_sysfs:
>  	f2fs_exit_sysfs();
> +free_garbage_collection_summary_cache:
> +	f2fs_destroy_garbage_collection_summary_cache();
>  free_garbage_collection_cache:
>  	f2fs_destroy_garbage_collection_cache();
>  free_extent_cache:
> @@ -5172,6 +5177,7 @@ static void __exit exit_f2fs_fs(void)
>  	f2fs_destroy_root_stats();
>  	f2fs_exit_shrinker();
>  	f2fs_exit_sysfs();
> +	f2fs_destroy_garbage_collection_summary_cache();
>  	f2fs_destroy_garbage_collection_cache();
>  	f2fs_destroy_extent_cache();
>  	f2fs_destroy_recovery_cache();
> -- 
> 2.33.0
> 
> 
> 
> _______________________________________________
> Linux-f2fs-devel mailing list
> Linux-f2fs-devel@...ts.sourceforge.net

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